The present invention relates to an automatically operating apparatus for feeding one or more elongate workpieces, such as strip-metal, tubular sections or profiled sections, to one or more working machines, for example shearing machines, punching machines, stamping machines, drilling machines and/or welding machines. The feeding apparatus is constructed for intermittently feeding stepwise an elongate workpiece along a given path and comprises, inter alia, a fixed and a movable clamping element. The workpiece is clamped in the movable clamping element and moved thereby to the working machine, with the fixed clamping element out of engagement with said workpiece. When the grip of the movable clamping element is released and said element is withdrawn, the workpiece is released therefrom and the fixed clamping element is moved into engagement with said workpiece. The length of the path of movement of said elongate workpiece is determined by limit switches arranged at respective ends thereof.
Known feed mechanisms of the aforedescribed kind are encumbered with a number of disadvantages. For example, the clamping force exerted by the movable clamping element is not always satisfactory. Further, since the aforementioned limit switches are not normally provided with the feeding apparatus when purchasing the same, they must be bought separately and installed by the customer, thereby complicating the process of setting those feeding apparatus available on the market at present to the correct length of feed stroke.
One object of the present invention is to provide a novel feeding apparatus of the aforedescribed kind which is reliable in operation and with which the length of feed stroke can be readily adjusted, and with which said length of feed stroke can be finely adjusted while the apparatus is in operation. A further object of the invention is to provide a feeding apparatus which, while operating at a high speed, requires the minimum of energy, and which can be readily adapted to work with different working machines.
Accordingly the present invention comprises an apparatus for intermittently feeding elongate workpieces stepwise in the direction of their longitudinal axis along a given path, said apparatus including a frame structure having a drive unit and a fixed clamping element; a further clamping element arranged for movement along said path, said further clamping element being so arranged that it will advance the workpiece when moving in one direction but will not move said workpiece when moving in the opposite direction, characterized in that the movable clamping element is connected, through a piston rod, to a piston which, in the direction of said movement path, cooperates with a pressure cylinder having a rear end plate which is displaceably arranged in said cylinder so as to alter the volume thereof and therewith the length of stroke of the movable clamping element; and in that a clamping ring which is displaceable on said cylinder is arranged to be clamped around the cylinder in a manner such as to compress the same around said end plate for fixing said plate in the desired position along the length of the cylinder.